DEVELOPMENT OF UMARC (UNIVERSITY OF MARYLAND ADVANCED ROTORCRAFT CODE)

A comprehensive rotor code is being developed which offers a user-friendly environment, coding modularity, finite element methodology, numerical robustness and computational efficiency The rotor-fuselage equations are formulated using Hamilton’s principle and are discretized using finite elements in space and time. The blade is considered elastic undergoing flap bending, lag bending, elastic twist and axial deflections. The finite element formulation allows the code to analyze a wide range of rotor designs. The blade airloads can be computed using quasisteady aerodynamics, linear unsteady aerodynamics (attached flow) or nonlinear unsteady aerodynamics (separated flow and dynamic stall). The options for steady-state rotor wake modeling are: a simple Drees' model, a prescribed wake model, and a free wake model. Dynamic inflow modeling is used for unsteady wake inflow computations. Selected results are presented to demonstrate the modeling and analysis capabilities of the code. Predicted stability, response and blade loads are validated with experimental data for several configurations including typical articulated, hingeless and bearingless rotors.